It is known to apply automotive trim pieces to the exterior of wheeled vehicles such as cars and trucks. Examples of such trim include accent stripes, side door bumper elements, upper and lower bumper covers, air damns, A B C & D pillars, claddings, wheel covers, grills, moldings, appliques, wheel flare moldings, body panels, and bumper fascia. The instant invention further applies to exterior vehicle components which have previously been made of plastic materials, such as sides and the like.
Exterior molded automotive trim components are typically painted in order to provide them with color. It is desirable that the paint color be compatible with the appearance of the vehicle (e.g. matching that of the vehicle, or complimentary thereto). Following painting of a molded piece of trim, a clear coat is often sprayed over the paint to give it luster.
Unfortunately, spray painting of molded components for use on vehicles is often undesirable due to the potential for resulting paint lines, a need for masking, and/or the corresponding labor involved. Moreover, spray painting is sometimes undesirable due to the high capital equipment cost associated with paint line equipment, and/or potentially hazardous environmental issues relating to solvents and the like. Thus, it will be apparent to those of skill in the art that it would be desirable if automotive trim components could be manufactured in a manner so that they were color compatible (e.g. matching, or aesthetically pleasing complimentary or non-matching) with automotive exteriors, without the need for spray painting.
U.S. Pat. No. 5,037,680, the disclosure of which is incorporated herein by reference, discloses a trim product made as follows. As discussed at col. 6, lines 15–45 of the '680 patent, a thermoplastic resin is transformed during an injection molding process into a shaped substrate in the form of a bumper fascia. Thereafter, a clear coat is deposited thereon by brushing, spraying, dipping, or flow coating. Unfortunately, this method is problematic for at least the following reasons. First, as the semi-molten colored material flows into the injection molding cavity color pigments therein may tend to collect at corners, bosses or edges due to flow patterns and/or different thicknesses in the cavity. This may result in certain areas of the product being colored differently than others. Second, metallizing material is not disclosed as being introduceable into the colored material in the '680 patent. Third, color pigment distribution may be non-uniform and/or inconsistent because of the disruptions during introduction of molten thermoplastic resin into an injection molding device (e.g. after the injection molding cavity has been filled, introduction of the resin is stopped until the next shot). Again, this may lead to inconsistent coloring of the final product(s). Fourth, it is sometimes but not always undesirable to use solvents in the application of the clear coat for environmental reasons. It is a purpose of this invention to overcome any or all of these problems.
Other problems with injection molding of colored materials are as follows: a) problems molding metallics as they tend to swirl or collect at gate(s) and other distinct features; b) difficulties in controlling gloss as the temperature of the mold required for optimum color material flow may not result in desired gloss; and c) ghosting.
Another approach to automotive trim coloring includes the use of dry paint film. Dry paint film technology is disclosed, for example, in U.S. Pat. No. 5,725,712, the disclosure of which is hereby incorporated herein by reference.
Prior art FIGS. 1–10 will be referred to for the purpose of describing conventional dry paint film technology. Automobile 1 of FIG. 1 includes bumper fascia 3, wheel covers 5, and other exterior components which may be made via injection molding technology. The first step is the provision of dry laminate 7 of FIG. 2, including self-supporting carrier sheet 9 (i.e. casting film), clear coat 11, paint coat 13, and optional size coat 15 for providing adhesion to a backing sheet in a subsequent laminating step. Clear coat 11 is coated onto carrier 9 by a complicated reverse roll coating process shown in prior art FIG. 3, in which clear coat lacquer is contained in coating pan 17. Applicator roll 19 picks up lacquer from the pan and coats it onto carrier film 21 (or 9) after it passes over guide roll 23. After exiting the nip (or die) between applicator roll 19 and rubber backup roll 25, the coated carrier film 27 passes to a multiple zone drying oven. After drying, a two layered laminate, including carrier 9 and clear coat 11, is provided.
Color coat 13 is bonded to clear coat 11 after the clear coat has dried on carrier 9. Color paint coat 13 is typically applied to the carrier by reverse roller coating techniques as shown in FIG. 3, with the color coat being dried by passing it through the multiple drying zones discussed above in curing the clear coat. Thus, the complicated reverse rolling techniques and multi-zone drying ovens of FIG. 3 are utilized on numerous occasions. Size coat 15 is next coated onto paint coat 13. The result is laminate 7 of FIG. 2.
Laminate 7 is laminated to a backing sheet by dry paint transfer laminating techniques shown in FIG. 4, to form laminate 29 of FIG. 5. During this laminating step of FIG. 4, paint-coated laminate 7 is stored on roll 31 and a flexible backing 33 is stored on roll 35. When rolls 31 and 35 unwind as shown in FIG. 4, and the webs respectively pass over drums 37, laminate 7 and sheet 33 are bonded together between heated laminating drum 39 and roll 41. The resulting laminate 29 then passes onto storage drum 43. The result is a roll of laminate 29 of FIG. 5, including a color determined by the colored pigment in paint layer 13. Laminate 29 includes backing sheet 33, size coat 15, color coat 13, and clear coat 11.
Next, laminate 29 is thermo-formed into a desired three-dimensional shape. Referring to FIG. 6, laminate 29 is placed inside clamping frame 45 of a vacuum-forming machine. Frame 45 is moved into oven 47 for heating laminate 29. Backing sheet 33 is heated in oven 47 and laminate 29 sags as shown at 49. Then, clamping frame 45 is moved back to the position above vacuum-forming buck 51. The preheated laminate 29 is vacuum-formed into a desired shape by drawing a vacuum on buck 51 through connection 53 to a vacuum pump, and buck 51 is raised to its FIG. 7 position. Vacuum is pulled through holes in buck 51 to force the pre-heated plastic of laminate 29 into the shape of the working surface of buck 51.
Next, shaped laminate 29 is bonded to a substrate panel as shown in FIGS. 8–9. Laminate 29 is placed in an injection mold and fused or bonded to the face of an injection molded substrate 55. FIG. 8 shows laminate 29 placed in the mold cavity between front and rear mold halves 57 and 59. Surface 61 may be a rigid, high gloss, highly polished surface. After laminate 29 is in place, semi-molten injection molding material 55 is injected into the mold through passage 63 behind laminate 29. The molding material conforms to the shape of the mold cavity and is permanently fused to backing sheet 33 of laminate 29 in the mold. A cross-section of the resulting three-dimensionally molded trim component is shown in FIG. 10.
As can be seen above, dry paint film transfer technology may be burdensome and complicated. For example, the aforesaid process illustrated in FIGS. 1–10 requires going through rollers and dryers on numerous occasions, as well as the required time to do same. Moreover, it has been found that the life span of such trim components may be limited because they can lose color quickly upon exposure to heat, sun, chemicals, or the like. The film is expensive, especially in small batches, and sometimes has limited elongation which limits drawing ability. Problems have also been experienced with regard to maintaining DOI (depth of image), in that DOI may be lost due to deep draws in the components. Depth of pockets or corners in the final molded components is also limited due to the dry paint film, as it may not be over-stretched or it may lose color and/or gloss.
It is apparent from the above that there exists a need in the art for colored and molded automotive trim components/parts which: (i) may be manufactured without the requirement of prior art dry color paint film transfer; (ii) are colored so as to match or compliment a color of the surrounding vehicle; (iii) may be manufactured at a reasonable cost; (iv) have an adequate life span upon exposure to heat, sun, chemicals, and/or the like; (v) may be manufactured without excessive capital expenditure; (vi) substantially maintain DOI; (vii) are scratch resistant, have luster, and are resistant to marring; (viii) have high gloss and retention of same; (ix) have color uniformity; (x) are resistant to gasoline, solvents and/or acid spotting; (xi) have satisfactory hardness and/or abrasion resistance; (xii) have satisfactory impact strength; (xiii) have acceptable UV resistance; (xiv) are resistant to water and humidity exposure; (xv) may be manufactured without the need to “spray” on clear coats with solvents; (xvi) may be made so that color pigment material in the product is approximately consistently distributed throughout at least one color layer; (xvii) may be made so as to have generally consistent coloration throughout at least one color layer; (xviii) may be made so as to reduce flaws such as flow lines, knit lines, sinks and/or the like; (xix) may be made so that metallizing material/particles can be approximately uniformly distributed throughout at least one color layer(s) of the product; and/or (xx) may be made using readily available industrial equipment such as vacuum forming devices, extrusion devices and/or injection molding machines. There exists a need in the art for molded trim product(s)/part(s) having any or all of the aforesaid characteristics, as well as methods of manufacturing the same.
It is a purpose of this invention to fulfill any and/or all of the above-described needs in the art, as well as other needs which will become apparent to the skilled artisan from the following detailed description of this invention.